Houston's rookie shortstop is back in leadoff spot and has slash up to .281/.352/.384. He's been on a particular tear over his last 10 games: .350 average, 10 runs, six steals, even a homer. Villar would carry a notable value strictly from the willingness to run, but now that he's actually getting on base (and the walk rate is fine), he becomes a must-own. And this addition is available to you in 90 percent of Yahoo! leagues.

Scooter Gennett is another middle infielder with a modest ownership tag (23 percent); all he's done is whack the ball at a .342 clip since his recall, with six homers. The power wasn't supported during his Triple-A time this year, but playing time and a hot bat is enough to sway me to a pickup at this stage of the season. Gennett also carries dual-position eligibility (second/short), always a welcome thing.

If you need some infield pop and can live with a hacking approach, maybe Jedd Gyorko becomes a pickup of interest. Gyorko has 10 homers over his past 44 games, despite a puny .213 average and an abysmal K/BB rate. But if you're locked into your batting-average position and strictly need the power numbers, Gyorko becomes a defendable addition. He's unowned in about two-thirds of Yahoo, and you can slot him at second or third.